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<h1>Setting up a Unix <tt>lpr</tt> filter for Ghostscript</h1>

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<h2>Table of contents</h2>

<blockquote><ul>
<li><a href="#Overview">Overview</a>
<li><a href="#What_it_can_do">What it can do</a>
<li><a href="#Setting_up">Setting it up</a>
<ul>
<li><a href="#Editing_device_list">Editing the device list <code>DEVICES</code></a>
<ul>
<li><a href="#Field_bpp">Field 1: bits per pixel</a>
<li><a href="#Field_colours">Field 2: colours</a>
<li><a href="#Field_dq">Field 3: dual queues</a>
<li><a href="#Device_example">Example definition of <code>DEVICES</code></a>
</ul>
<li><a href="#Editing_filter_list">Editing the filter list</a>
<li><a href="#Editing_printer_port">Editing the printer port and type</a>
<li><a href="#Modifying_printcap_insert">Modifying <code>printcap.insert</code></a>
<li><a href="#Multiple_queues">Single or dual queues</a>
</ul>
<li><a href="#Bugs">Bugs</a>
<li><a href="#Authors">Authors</a>
</ul></blockquote>

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<p>For other information, see the <a href="Readme.htm">Ghostscript
overview</a> and the <a href="Use.htm">usage documentation</a>.

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<h2><a name="Overview"></a>Overview</h2>

<p>
"How do I set up Ghostscript to provide PostScript queues in a standard lpr
environment on Unix systems?" is a Frequently Asked Question amongst
Ghostscript users.  The two shell scripts described by this document are
designed to make this task a little easier. They are

<blockquote><dl>
<dt><code>unix-lpr.sh</code>
<dd>a flexible, multi-option print filter

<dt><code>lprsetup.sh</code>
<dd>A shell script which sets up soft links and creates a template insert
for the <code>printcap</code> file
</dl></blockquote>

<hr>

<h2><a name="What_it_can_do"></a>What it can do</h2>

<p>
The print filter resides in the Ghostscript installation directory (often
<code>/usr/local/share/ghostscript</code>, but may be something else at
your installation), together with a dummy filter directory containing
various soft links which point to the filter. It offers the following
features:

<ul>
<li>Multiple devices supported by a single filter
<li>Multiple bit-depths for the same device
<li>Multiple number of colours for the same device
<li>Direct (single-queue) and indirect (two-queue) setup
<li>Support for the standard preprocessing filters if you have the
corresponding (whatever)-to-PostScript translators
<li>Redirection of diagnostic and programmed output to a logfile in
the spooling directory
<li>Maintaining of printer accounting records of the numbers of pages
printed by each user (compatible with the <code>pac</code> command)
<li>Straightforward editing for further customisation
</ul>

<hr>

<h2><a name="Setting_up"></a>Setting it up</h2>

<p>
The <code>lprsetup.sh</code> script needs to have two lines edited
before running, to set the printer devices to use and the list of filters
available. With this information, it

<ul>
<li>creates a "<code>filt</code>" subdirectory under the
Ghostscript installation directory
<li>creates the links in this directory which enable the filter to
determine the parameters for running Ghostscript
<li>automatically generates <code>printcap</code> entries which should
need only a little editing before adding to your system
<code>printcap</code> file
</ul>

<h3><a name="Editing_device_list"></a>Editing the device list <tt>DEVICES</tt></h3>

<p>
At the top of <code>lprsetup.sh</code> is a line of the form
<code>DEVICES=</code><em>{list}</em>.  Replace the example list with
your own list of devices.  Each entry is the name of a device, followed by
three more optional fields, separated by dots "<code>.</code>".

<h4><a name="Field_bpp"></a>Field 1: bits per pixel</h4>

<p>
The first field is required only if the printer device understands the <a
href="Devices.htm#deskjet_parameters"><code>-dBitsPerPixel=</code>
switch</a>, which applies only to colour devices. For a particular number
<b><em>N</em></b> of bits per pixel, add the suffix <b><em>.N</em></b> to
the device name, for instance <code>cdj500.3</code>,
<code>cdj500.24</code>, etc.

<h4><a name="Field_colours"></a>Field 2: colours</h4>

<p>
The second field is required only if the printer device understands the
setting of the <code>Colors</code> device parameter (as in
<code>-dColors=</code>), which applies only to colour devices (and at
present is only supported by the <code>bjc</code>* family of drivers).
For a particular number <b><em>N</em></b> of colours, suffix
<b><em>.N</em></b> to the device name, such as <code>bjc600.24.3</code>,
<code>bjc600.8.1</code> etc.

<h4><a name="Field_dq"></a>Field 3: dual queues</h4>

<p>
The third field is required in order to use two separate queues for the
device, a "raw" queue and a PostScript queue (see
"<a href="#Multiple_queues">Single or dual queues</a>" below).  If you want
dual queues, add the suffix <code>.dq</code> ("dual queue") to the name,
whether or not a <a href="#Field_bpp">bits-per-pixel suffix</a> has already
been added.

<h4><a name="Device_example"></a>Example definition of
<tt>DEVICES</tt></h4>

<p>
Thus the following list supports a <code>cdj550</code> device at three
different bit depths (24 bpp, 3 bpp and 1 bpp), with a dual queue (that is,
a separate queue for the raw data); a monochrome <code>deskjet</code>
device with a single queue; and a <code>djet500</code> device using a
separate queue:

<blockquote><code>
DEVICES="cdj550.24.dq&nbsp;cdj550.3.dq&nbsp;cdj550.1.dq&nbsp;deskjet&nbsp;djet500.dq"
</code></blockquote>

<h3><a name="Editing_filter_list"></a>Editing the filter list</h3>

<p>
The standard list contains only the generic "<code>if</code>" filter,
but a commented-out list shows other filters which may be available.  If
you wish to use the support for these filters, you may need to edit the
<code>bsd-if</code> file to add to the <code>PATH</code> the
directories where the translators are stored, or to change the names of the
filters if yours are different.  The <code>bsd-if</code> script is
supplied with an example setup using Transcript (a commercial package from
Adobe), and PBMPLUS, a freeware package by Jef Poskanzer and others.

<h3><a name="Editing_printer_port"></a>Editing the printer port and
type</h3>

<p>
You can set the port and port type (parallel or printer) for an attached
printer, but for remote printers you'll have to modify the
<tt>printcap.insert</tt> file yourself.

<h3><a name="Modifying_printcap_insert"></a>Modifying
<tt>printcap.insert</tt></h3>

<p>
Running <code>lprsetup.sh</code> generates a file
<code>printcap.insert</code> which has a template setup for your
printer queues.  It cannot guarantee to do the whole job, and you will
probably need to consult your system documentation and edit this file
before you add it to your <code>printcap</code> file.  The file has good
defaults for serial printers, as these often cause problems in getting
binary data to the printer.  However, you may need to change the baud rate,
or the handshaking method.  Only a small change is required in the
<code>printcap</code> file to use a networked remote printer instead of
an attached printer, and an example is given in
<code>printcap.insert</code>.

<h3><a name="Multiple_queues"></a>Single or dual queues</h3>

<p>
If you wish to provide a PostScript-only queue (for example, so that all
pages printed go through accounting), and the printer port is local to the
host machine, a single queue is appropriate -- Ghostscript simply converts
PostScript into the printer's native data format and sends it to the
port.  But if the printer is on a remote networked machine, or if you need to
send raw printer data to the printer, you must use two queues.  Simply
specify the <a href="#Field_dq">"<code>.dq</code>" option</a> above.

<hr>

<h2><a name="Bugs"></a>Bugs</h2>

<p>
You must have write access to the Ghostscript installation directory for
<code>lprsetup.sh</code> to create the filter directory and soft links.

<p>
If you have several different values of bits per pixel for the same device,
you must list all instances of that device as adjacent items in the
<a href="#Editing_device_list"><code>DEVICES</code></a> device
list.  If you do not, <code>printcap.insert</code> will contain multiple
entries for the same device, which is not supported.

<hr>

<h2><a name="Authors"></a>Authors</h2>

<p>
This material was contributed by George Cameron.  Yves Arrouye
&lt;<a href="mailto:yves.arrouye@usa.net">yves.arrouye@usa.net</a>&gt;
is responsible for the number-of-colours part of the script.

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<p>
<small>Copyright &copy; 2000-2006 Artifex Software, Inc.  All rights reserved.</small>

<p>
This software is provided AS-IS with no warranty, either express or
implied.

This software is distributed under license and may not be copied, modified
or distributed except as expressly authorized under the terms of that
license.  Refer to licensing information at http://www.artifex.com/
or contact Artifex Software, Inc.,  7 Mt. Lassen Drive - Suite A-134,
San Rafael, CA  94903, U.S.A., +1(415)492-9861, for further information.

<p>
<small>Ghostscript version 9.19, 23 March 2016

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